[Intel-gfx] [PATCH] drm/i915/execlists: Explicitly reset both reg and context runtime

[Chris Wilson]

Upon a GPU reset, we copy the default context image over top of the
guilty image. This will rollback the CTX_TIMESTAMP register to before
our value of ce->runtime.last. Reset both back to 0 so that we do not
encounter an underflow on the next schedule out after resume.

This should not be a huge issue in practice, as hangs should be rare in
correct code.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/gt/intel_lrc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index b12355048501..b458f8e17cf5 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1154,6 +1154,7 @@ static void restore_default_state(struct intel_context *ce,
 		       engine->context_size - PAGE_SIZE);
 
 	execlists_init_reg_state(regs, ce, engine, ce->ring, false);
+	ce->runtime.last = intel_context_get_runtime(ce);
 }
 
 static void reset_active(struct i915_request *rq,
@@ -4581,6 +4582,7 @@ static void init_common_reg_state(u32 * const regs,
 	regs[CTX_CONTEXT_CONTROL] = ctl;
 
 	regs[CTX_RING_CTL] = RING_CTL_SIZE(ring->size) | RING_VALID;
+	regs[CTX_TIMESTAMP] = 0;
 }
 
 static void init_wa_bb_reg_state(u32 * const regs,
-- 
2.20.1